


Inverto

by nocturnias



Category: Sherlock (TV)
Genre: Alpha Molly, Anal Fingering, F/M, First Time, Mating Cycles/In Heat, Omega Sherlock, Omega Verse, Plot What Plot/Porn Without Plot, Soul Bond, vaginal teeth
Language: English
Status: Completed
Published: 2013-05-30
Updated: 2013-09-13
Packaged: 2017-12-13 10:49:06
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 6,297
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/823461
Author URL: https://archiveofourown.org/users/nocturnias/pseuds/nocturnias
Summary: <blockquote class="userstuff">
              <p>Omegaverse AU. A lab experiment gone wrong changes Molly to an Alpha and Sherlock to an Omega.</p>
            </blockquote>





	1. A friend in need's a friend indeed

**Author's Note:**

  * For [PetraTodd](https://archiveofourown.org/users/PetraTodd/gifts), [broomclosetkink](https://archiveofourown.org/users/broomclosetkink/gifts), [Whytejigsaw](https://archiveofourown.org/users/Whytejigsaw/gifts).



> Chapter titles are lines from the song "Pure Morning" by Placebo. 
> 
> I own neither Sherlock nor the Placebo song. This is not intended as copyright infringement and no gain, monetary or otherwise, is received for the writing of this work of fanfiction.

**Summary for the Chapter:**

> An accident in the lab has extraordinary consequences for Sherlock and Molly.

Molly groaned and slowly turned over. Every muscle she owned protested at the movement, and a few she hadn’t known she possessed. As the violet-blue haze cleared in the lab, she sat up, absently rubbing the back of her neck. What happened in here?

Then, like a restless wind, it came rushing back into her head.

The experiment.

The accident.

Sherlock.

“Sherlock?” she called sharply, coughing a bit as she rose to her feet. The vapors were dissolving around her like will-o-wisp trails. Other than the shattered beakers on the floor, there was now no discernible sign of the incident that had sent both her and Sherlock flying to the floor.

She heard a soft moan coming from behind the desk, and though she stumbled a bit Molly managed to get to her feet. Carefully avoiding the broken glass, she followed the direction the moan had come from, and found Sherlock on the floor on his back, one arm flung up over his face.

She knelt beside him. “Sherlock. Are you all right?” She looked him over while he groaned.

“Seem to be.” He moved his arm down and opened his eyes, looking up at her. “That was quite a conclusion to our experiment. Did you preserve a sample of the substance?”

Molly shook her head. “There’s nothing to preserve. It all turned into a violet-blue vapor and dissipated. Nothing left but two broken beakers.”

“Well that’s a disappointment,” Sherlock said, frowning. “And you’re certain you don’t know what was in the other beaker?”

“No, except that someone had accidentally swapped our formula out with something. We can always go ask around, see what we can find.” Molly stopped, frowning. Something smelled different in the room. It was slightly tart, but sweet at the same time. It smelled like jasmine and paprika and dark red cherries, and her mouth nearly watered in response.

“Molly?”

Dimly, Molly heard Sherlock saying her name. But she couldn’t fully hear him over the sudden deafening roar of her heart in her ears. It pounded relentlessly like a tidal wave. Her entire body seemed to throb and she clenched her hands to keep them from trembling.

“Molly?” Sherlock’s voice grew insistent. “Are you all right?”

She shivered softly at the sound of his voice. That deep, beautiful voice, like warm cream. The room seemed too small suddenly. Molly struggled to think, the smell getting stronger as Sherlock sat up, and with a sudden dismaying rush of clarity she knew where it was coming from. Him.

She turned to look at him.

Sherlock stared at her, puzzled. She looked different, somehow. Come to think of it, he felt a bit off. Not like his usual Alpha self. It had been replaced with something: the urges, the rampant hormones that he worked hard to keep under control. He felt… gentler somehow. Mellow. It was strange, but a welcome change from having to feel physical pressure. The Alpha urges were demons he had to fight down daily, his massive intellect warring with his dominant biology.

He’d never wanted to be an Alpha. He was a man of reason and science. He had better things to do than preen and strut and mate on demand like a breeding animal. Mycroft’s “suggestion” that he take an Omega had been the last straw. Surely there was a way to change the body chemistry, he’d reasoned. He’d toyed with the idea before but now had seemed like the time to put it into practice. So he’d set up in an auxiliary lab at Bart’s, and had coaxed/charmed Molly into helping with the promise of dinner every night (“Real dinner, Sherlock, not crisps or biscuits or a bag of takeaway!”). Things were looking promising, and Sherlock for the first time saw a light at the end of the Alpha tunnel. Now it was all lost.

But what had the accident done to him? And Molly? He looked her over. Pupils dilated nearly to nonexistence, heart rate elevated, flushed face, something different about her expression and her posture, too. She looked primal somehow, as though she wasn’t an Omega anymore but an ….

Oh, dear.

Molly moved closer to him. He swallowed hard. “Molly…”

“You smell delicious,” she whispered roughly.

“Molly, we need to talk,” Sherlock said quickly.

“Not interested,” she said, her voice near a growl.

“The experiment, Molly. It’s changed us. Turned you into an Alpha and me into an Omega. You’re reacting to my chemistry, Molly, that’s all.”

She took a ragged breath, trying to calm herself. Unfortunately for Sherlock, her nearness and their reversed polarity wasn’t just having an effect on Molly. Now he was struggling with new, different urges: to offer her his neck, to touch the thundering pulse at the base of hers, to arch his body beneath hers while she was crushed against him. No, no, no. This wouldn’t do at all. They had to separate for now, cool down, figure out what to do…

He felt dizzy. His entire body seemed to burn. He could feel the flush in his cheeks: feel it starting to spread to his neck. His eyes widened in dismay. He knew what this was. Not only had they been reversed, he was in the early stages of heat. Alone in a room with an Alpha whose chemistry was extremely compatible with his. He’d felt it before, of course: when he was an Alpha and she’d been his adoring Omega. He’d always managed to tamp it down before: meditate, focus on a case, or at times cruelly push Molly away verbally. It had all been to stop himself from getting closer to her: from rejecting his urges to mate, to bond.  There wasn’t room for that in his life, not even with Molly.

The sudden shift in his perspective from Alpha to Omega was changing that. All he wanted was her: to belong to her, to feel himself filling her up as she claimed him. It was equally mad, wasn’t it?

He started to get up, but Molly pushed him back down. “Where do you think you’re going, Sherlock?” She asked, and the edge in her voice sent shivers down his spine in an exquisite electric tingle.

“Molly. Listen to me. I am in heat. We’re responding to each other. We have to get out of here and separate until it abates. Then we can figure out a plan.”

“Why?” She asked. “Why do we have to separate? You want me, I know you do. I can smell it. Besides. If we don’t get you out of heat, another Alpha will try to claim you. You might even incite blood lust.” Her fingers slid down to his chest, sliding buttons open, her hands splaying on his skin.

“I can take a suppressant-”

“It’s too late once you’re already in heat, and you know that.” Her hand moved up to caress his face, and he sighed deeply as her touch eased his ache a bit. The logical solution was to get this out of their systems. He knew that. But the thought of giving in to something he’d never given in to before made him afraid.

Molly cupped his face in her hands. “You said you trust me. Then trust me now.”

Sherlock looked into her warm brown eyes. Alpha or Omega, he did trust Molly. And there was no denying that they had to do something about this sudden reversal. The tension between them was so taut it was a breath away from snapping like a violin string.

He breathed slowly to steady himself, then nodded. “I’ve always trusted you. Baker Street is closer than your flat. Come with me, Molly Hooper.”

Molly grinned and placed the lightest of kisses on his mouth. “We’ll see what we can do, Sherlock Holmes.”

 

 

 


	2. A friend who'll tease is better

**Summary for the Chapter:**

> Sherlock and Molly make plans and get to 221B.

**Notes for the Chapter:**

> Wow, thank you all so much for the love! 
> 
> I don't own Sherlock or make any money from this fic.

He had enough presence of mind to send two quick texts. Molly ran her hands over him the entire time, curls to toes. He didn’t try to stop her: it kept her distracted while he took care of the important things.

Sherlock knew they shouldn’t take the tube, or even a cab. At the rate they were going, neither of them would be able to maintain decorum in public. He was a known Alpha, and if he was seen submitting to Molly, there would be questions and prying that he didn’t want.

His first text was to Mycroft. _Send a car immediately to Bart’s. Destination is 221B. Time is of the essence._

He didn’t elaborate, and his brother would not ask questions. Not yet. There would be lots of questions later, but later was later. His next text was to John, while Molly ran her fingers roughly through his hair and nipped at the base of his neck.

_Leave the flat if you’re there. Don’t return until you hear from me. Could be several days._

John, of course, didn’t hesitate to ask questions. _Why? What’s going on? Are you all right?_

_No,_ Sherlock thought, gasping as Molly started licking his ears, _I am not all right. I’m an Omega in Stage One heat being ravished by my friend and pathologist, who has become an Alpha and turned into a sex maniac._ He gritted his teeth and typed: _Fine. Please just do as I ask. I am on my way now with Molly._

He knew that mentioning Molly would delight John and make him think that all his lectures to Sherlock about her had finally paid off. His best friend had suggested that Sherlock and Molly bond on more than one occasion, ever since John had met and married Mary. They were both Betas, and living a happy loving existence free from the madness and lust that afflicted Alphas and Omegas.

Or maybe John would think Molly was in heat and Sherlock had decided to give in to his Alpha urges. Ugh. That smacked of one of those so-called romance novels where Alpha males ravished Omega females.  There were female Alphas, of course, and Omega males: it was just uncommon. Recent scientific studies put only 1 out of every 25 females as Alphas. Sherlock was jolted from his statistical musings by the feeling of hot, wet lips below his ear.  

“Molly,” Sherlock moaned, as Molly found a tender spot on the side of his neck. She yanked the top button off his shirt and nuzzled deeper, inhaling sharply. “Molly!” Sherlock said loudly.

“Your shirt’s unbuttoned. I can smell your neck,” she growled, and she pressed her mouth to the soft white skin and began to suck. Sherlock’s arms came up around her and he gasped. He’d had less than no idea how this would feel. He shook his head to clear the red haze of hunger.

“The car is coming. We have to go,” he told her.

Somehow, Molly controlled herself enough to move away from him and they quickly stood up. Sherlock rapidly re-buttoned his shirt and they left the lab.

Molly managed to control herself as they exited the hospital, and except for a brief second when she grabbed his hand in a crushing grip at the car, she continued to maintain her outward composure. Sherlock sighed in relief. It seemed they would be all right until they were safe in the privacy of 221B.

As soon as the car started to move, however, he realized he’d made a mistake in believing that. Molly was on him so fast he barely had time to gasp in surprise. She took advantage of his slightly open mouth and teased the corners with her tongue, eliciting another gasp from him. When had his mouth become so sensitive? Oh, yes. Since he’d become an Omega in Stage One heat.

“Molly,” he said, glancing at the dark partition separating them from the chauffer. “The driver-“

“Sod the driver,” Molly said, shoving Sherlock’s coat aside so she could get at his neck again. “Let him find his own Omega.”

Sherlock now realized his earlier error in comparing this to a romance novel. It wasn’t romantic. It was porn: pure hormone-driven, frenzied porn. Molly was breathing him in as though he was air, nearly clawing at his buttons in her haste to get them undone, and Sherlock felt a mix of alarm and arousal tighten in his gut as his body reawakened and surged in response to hers.

“Molly, no! We’re almost there!” He hissed at her, wondering if they’d manage to even get in the flat. The look in Molly’s eyes, a combination of ferocious lust and erotic appreciation, made it clear to him that she was fine with taking him right there in Mycroft’s car.

“Stop!” he hissed again, pushing her away. She blinked several times and swallowed hard, the haze clearing a bit. “Why did you stop me?” She demanded.

“I stopped you because you wouldn’t want my-our-first time to be in my brother’s bloody car if you were in your right mind,” Sherlock snapped. “Speaking of that, I don’t know how long we have until I reach Stage Two, so we need to talk about a few things, quickly.”

“Oh, God, just like an Omega. All talk and no action,” Molly groaned.

“I beg your pardon?” Sherlock asked indignantly.

“Mmm, beg, now we’re getting somewhere,” Molly said with a smirk.

“Molly I realize that right now you have effectively turned into a hormone-riddled teenager, but would you please try to focus?”

She groaned. “You have **no** idea how difficult that is right now.”

“Oh, I wouldn’t go **that** far,” Sherlock said acidly. “I was an Alpha until earlier today, remember? Now. Since you were an Omega, you’ve been on suppressants, yes? And birth control?”

She nodded. “That’s safe.”

“Good,” Sherlock said, nodding. “Call in at Bart’s. Tell Mike your time is upon you and you need the next four days off.”

“Four?” Molly asked, wide-eyed.

“We have been altered, Molly. To my knowledge, there is no known case of Alphas becoming Omegas and vice versa. We don’t know what is going to happen.”

“I can think of a few things,” Molly muttered.

“Molly! Stay focused! We’ll be at Baker Street in less than two minutes!”

“Fine!” she pulled out her mobile and called Mike Stamford, leaving him a message. “There. Anything else?” She asked.

“What about-”

“Shut up, my turn,” Molly said, and pounced on him. His mouth opened instinctively to the press of her lips, and she slid her tongue in to taste him. She evidently liked it, because she moaned and tugged him closer, opening his mouth further, holding him so tightly against her Sherlock felt for a brief flash that they had melded together. The events after the accident had all happened so quickly he hadn’t fully processed them all yet. Of course, that was also complicated somewhat by Molly’s tongue in his mouth.

“Molly, we’re here,” Sherlock said, and as if on cue he felt his body start to flush again, stronger this time. His nipples hardened and strained against the fabric of his shirt, and his cock went from zero to iron bar in less than five seconds. Molly gave a high-pitched cry into his mouth, and it took all his strength not to bare his throat to her, let her mark him as hers. “Molly! Come on!”

He pushed her away again and fumbled for the door handle as the car stopped, almost tumbling into the street. He ran a hand through his hair and hurried to the other side, opening Molly’s door and hauling her out. He pinched her arse, hard, and the shift from pleasure to pain refocused her again.

“Ow!” She exclaimed. “A little rough there, aren’t you?”

Sherlock pulled her close. “I’m entering Stage Two,” he whispered roughly in her ear. “Inside, NOW.”

**Notes for the Chapter:**

> Next up: PORN!


	3. My Friend Confessed, She Passed the Test

**Summary for the Chapter:**

> Sherlock and Molly fulfill their mating urges.

**Notes for the Chapter:**

> Thanks to everyone for reading, reviewing, and leaving kudos! The last chapter will be very long.

Once safely inside 221B, Sherlock locked the door: something that he didn’t often do. While normally he didn’t mind John or Mrs. Hudson popping in, this was definitely not a time for visitors.

The heat was progressing quickly. Normally Stage One lasted for hours, maybe even a day. Evolution had apparently wanted to assure that the mating drive gave the Alpha some time to get to the Omega, or for some other Alpha to, with enough warning to prepare for mating. Sherlock suspected whatever exactly had happened to them had accelerated what would be his normal biological process. Stage Two meant his hormones were going to get progressively stronger, filling both him and Molly with primal mating urges.

He sighed. At least it had happened with Molly, someone he trusted and cared for. As if on cue, he felt her nose nuzzling into his neck, heard her sharp intake of breath as she once again deeply inhaled his scent. He turned to face her. She moved back enough to stare up at him. Her fingers brushed his face and she smiled; the same sweet, earnest smile she’d always had for him as an Omega. She was trembling a bit, and her pupils had expanded so much that her irises were barely visible. He didn’t need to take her pulse to know it was thundering just below her skin.

He cleared his throat. “Bedroom’s this way,” he said, hearing the roughness in his voice.

Molly’s hand reached down and brushed his. Now that this was actually happening, she felt nervous despite her newfound Alpha status. “Are you sure about this?” She asked him softly.

He raised his eyebrows. “Isn’t that supposed to be my line?” He asked wryly, and she giggled.

His other hand came up and briefly brushed against her face. “Yes, I’m sure. There is no other person, Alpha or Omega, that I’d rather this happen with. When I said you’ve always counted and I’ve always trusted you, Molly, I meant it. Surely you know that.”

She nodded. Her trembling increased as her thumb brushed over his palm, and Sherlock felt his arousal surging. The resulting hormone flush triggered Molly’s hormones again, and she gripped his hand hard.

“Right,” she said, licking her lips. “You said something about your bedroom?”

Once they were in his bedroom, Molly pulled him to her, pulling him down and herself up so that she could kiss him. His lips parted easily against the insistence of her tongue and she moaned softly into his mouth. The whole thing seemed like a dream to her:  a dream that she wanted to go on forever. But she would enjoy it for as long as it lasted.

There was a sharp spike in his scent, and her hands gripped his waist as a new urgency hit her. She broke the kiss and groaned: “Sherlock, I- I don’t think I can-”

“-Hold out much longer,” he finished her sentence, gasping as her tongue laved over his jaw. “I know. As much as I am normally loathe to use clichés, I think it’s time we let nature take its course.”

They undressed each other, hands shaking, blood pounding, which led to two popped buttons and one zip that was possibly ruined for life. As soon as they were both naked, they didn’t lie on the bed so much as fall on it, Molly’s hands traveling over Sherlock’s body revently, possessively. Her hands tangled in his hair as she kissed him, her soft breasts and taut nipples pressed tightly to his chest.

Sherlock moaned and arched against her. His entire body hurt and his hard cock twitched against Molly’s stomach. He tilted his head back, offering her his throat, and her mouth moved down from his swollen lips to slide over that pale expanse of skin. Her teeth fastened on a soft spot near his carotid artery and she began to suck and bite, tugging the flesh into her mouth and working it between her teeth to leave the ritual mark that would determine their future together.

He moaned as she marked him, pressing his hips into hers and grinding his cock against her hot, wet sex. She finished with a loud, wet smacking sound and lifted her head to admire the blossoming purple bruise. Molly wanted to draw it out, to tease and worship him, but she simply couldn’t wait any longer.

She reached down and grasped Sherlock’s dick in one hand, planting the other on the side of the bed. She was ready, more than ready, lips slick and shining with arousal. They both gasped as she guided him into her. She was tight and he was big, so Molly took her time with him. She moved down inch by inch on him, slowly, until he was sheathed inside her.

Molly moved her hands to Sherlock’s chest, index fingers pressing on his nipples, rubbing them up and down. She folded her legs and rested her weight on them, then began to grind against him. Her hips rolled forward and back in time with his thrusts, and she quickened her pace as she felt his thigh muscles flex and his bollocks tighten when she brushed against them. Her movements grew less controlled, more frantic. It was so close, she could feel it, but she needed more.

Suddenly Sherlock grabbed her by the waist. He flipped them over, somehow managing to stay inside her, and pushed into her deep: deeper than any man ever had. His breath hissed between his teeth as he did, thrusting into her with several powerful strokes, and he buried his face into her neck as she cried out. Her thighs squeezed his hips and she tilted her body to meet his with every thrust.

“Oh, god,” she cried. He moved his face up so he could kiss her, and his lips on hers was all she needed to take her over the edge. She came with loud, hoarse cries, over and over, and her muscles clenched and clamped him inside her. She broke the kiss and threw her head back, eyes closed tight, crying: “Ahh!” and “Sherlock!” over and over.

Molly’s orgasm overwhelmed him. The feel of her, hot, and drenched in fluids, and her crying out his name sent him spiraling. He felt his cock expanding, the head still swollen, and the small part of him that could still think clearly realized that he was knotting. How was it possible? He’d been turned into an Omega. Only Alphas could knot. But he was. Sherlock stretched and filled her, his knot joining them fully together. Molly gave one long, high keen as the physical bond between them completed, eyes wide in the same shock that Sherlock felt upon realizing he was knotting inside her.

And then he came, all coherent thought fleeing as pure hormone-fueled pleasure raged through his body like wildfire. His cry mingled with hers as he stilled, his cum overflowing and spilling into her. His heart pounded and his blood roared in his ears, and he instinctively pulled her tightly to him, so many neurochemicals flooding his brain that he couldn’t process anything else. All he could do was dig his fingers into her back and moan until he rode his climax to the finish.


	4. And We Will Never Sever

**Summary for the Chapter:**

> Molly and Sherlock get some surprises as the Heat progresses.

**Notes for the Chapter:**

> Here be explicit subject matter. Thank you so much for reading, leaving kudos, and reviewing!
> 
> Yes, I am aware that vagina dentata does not really exist. Neither do Alphas, Omegas, Soul Bonding, Heat, and Knotting. :)
> 
> This is dedicated to whytejigsaw as a belated birthday gift. I hope it's bold enough, sweetie! ;)

Sherlock had no idea of how much time had passed when Molly shook him gently awake. He looked into her eyes, so dark and deep, and at her sweet, earnest face. The lust had temporarily abated; he was able to slip out of her, his cock returned to normal size. But they both knew it was not going to last long. A few hours: maybe a little more, maybe a little less. Then the heat and madness that they couldn’t resist would take them again.

Sherlock traced her features with an inquisitive fingertip: her petite, slightly upturned nose, her wide eyes, the mouth he’d commented on cruelly before. No, she did not have bee-stung lips. But they were soft and nicely shaped. And they were excellent for turning him into a total wreck. He’d seen plenty of women with large, pouty lips; seen them use those lips to say hurtful things, or manipulate. Molly’s lips would never do that; never be used as a weapon of pettiness or malicious deceit. Given the choice, he’d prefer her honesty, intelligence, and valor over a thousand Irene Adlers.

She smiled at him, reaching over to brush a lock of glossy, sweat-damp hair off his cheek. “I’m sure there’s something awkward and silly I could say, but I can’t think of it right now.”

He graced her with a small smile in return, huffing in quiet amusement at her words. “I could just as easily say something horrible, I suppose. Fortunately for us, in that regard, my brain is bathing in chemicals at the moment and doesn’t seem inclined to do so.”

She cuddled closer to him. “Hmm. Neither of us saying the wrong thing. How long do you suppose that can last?”

Sherlock laughed this time, and Molly smiled again. She loved his laugh. She loved everything about him, really; well, except when he was being an annoying git. That wasn’t going to be a problem; at least not until this was over.

“I think we’d best get some water in us to keep dehydration away,” she told him. “And eat something.”

He nodded in agreement, rising and stretching like a cat before offering her his hand. They briefly rummaged in the kitchen, then sat on the sofa together drinking water and sharing some biscuits and apple slices. They didn’t talk much, but the silence was comfortable, not awkward. Over the years they’d gotten used to each other, and after Reichenbach and all Molly’s help, Sherlock had treated Molly with more respect.

Sure enough, Two hours and eighteen minutes later, Sherlock felt his skin start to crawl. It was a curious sensation, not entirely unpleasant physically. But he knew that would change; knew that the crawl would then into an ache, one that he wouldn't be able to resist. Unfair, this; being first at the mercy of his overbearing Alpha hormones, now to be at the mercy of the Omega ones. At least the Omega ones could be scientifically suppressed after this. He just had to make it through this heat, with Molly's help.

At the thought of Molly, he looked up to see her staring at him. Were he an average Omega, he might be a bit frightened by the look in her eyes. But he was still Sherlock Holmes and all he felt was curiosity and lust.

Molly inhaled sharply, knowing by the look in his eyes that his heat had returned a second before she smelled it. And what an intoxicating smell it was, like spiced copper, which was an odd combination of scents but it seemed perfectly suited to him. She would be sore tomorrow, but that was tomorrow. For now there was only the pleasure.

Her fingers wound tightly in his curls and she kissed him, slowly at first, then he groaned eagerly into her mouth and what little control she had broke. Gentleness could only go so far when you were in heat; especially when you wanted someone as long as she had wanted Sherlock.

Their tongues tangled in each other's mouths as Sherlock splayed out his fingers over her breasts, curling them against the taut skin. His thumbs brushed her nipples and Molly moaned, arching against him. His hips molded against hers and he thrust them instinctively, felt the crisp curls of his pubic hair brush against the smoothness of her mound.

Molly's other hand reached between them to cup his bollocks, her small, strong fingers massaging their warm weight carefully. A deep groan ripped itself from Sherlock's throat and was swallowed up by her lips, still covering his with urgent possessiveness. She thrust her tongue into his mouth the way a man would thrust his cock into a woman's cunt, and it sent a frisson of pleasure down his spine.

She urged him down onto his back, enveloped by the warmth emanating from him as she slid her damp skin along his. Molly pressed her thumbs on the inside of his thighs, and they parted like water under her insistent touch.

Sherlock gasped as she lowered her head to his bollocks, drawing first one and then the other into her mouth, her wet, hot tongue lapping at them the way a cat would lap cream. As she did, she pressed on his perineum with a thumb, and he thrust his hips against her again. Each time she pressed there made another explosion go off in his brain, and his hips jerked like a puppet on a string.

Just when he thought he would be overwhelmed by the stimulation, Molly took her mouth off his balls. He moaned in protest, looking at her with eyes so darkened by lust they were the color of an angry sea. Before he had time to process what she was about to do, her mouth went to the area where her thumb had been, and one fingertip flicked over the rim of his arsehole.

If Molly's lips on his bollocks had halfway driven him mad, her finger flicking over that seemingly innocuous spot had him ready to declare himself insane. It awoke something in him he'd never even known existed and lit every nerve ending on fire. She repeated her actions and his hips shot up as he pressed himself harder against her mouth. "Molly," he gasped.

She chuckled low in her throat and started fingering him in earnest, gently slipping the digit inside and out, until she finally eased it high enough to softly massage his prostate. Sherlock twisted beneath her, gasps and moans escaping him before he even knew he was making the sounds, wanting more and more and more of this powerfully pleasurable experience. It was intensely intimate, almost painfully so, yet he didn't want it to stop.

When Molly started gliding a hand over his dick while touching him there, Sherlock thought he would explode. He jerked, he arched, he groaned and gave a hoarse, inarticulate cry that to his scrambled brain sounded like "Molly, please," and she removed her hands from him. He nearly howled in frustration and hunger. But she quickly straddled him and lowered the wet heat of her cunt onto his cock, slipping him effortlessly inside her with a soft gasp that was part ecstasy, part elation. 

She rocked against him as he thrust into her, burying himself as deep as he could inside her. Something was different this time; he sensed it immediately. His dick no longer felt as though it was going to expand and knot her. It felt; well, he had no comparison, but he imagined it felt like an Omega’s cock would. The acceleration of their transformation was astounding, and despite the wild ecstasy running through him, the scientist in Sherlock took a few seconds to appreciate the changes.

Molly’s eyes widened; she, too, had realized the difference. And if they were truly converted from Alpha to Omega and Omega to Alpha, then that also meant that…

Molly cried out with a high-pitched wail as an orgasm rippled through her, leaving her overwhelmed and shuddering. Her sweat-slicked skin clung to his as she pumped her hips two more times, and that was all it took to send Sherlock over. As his come filled her, they both felt small, hard protrusions inside her, forming a circle around his dick, and Sherlock was gently but firmly gripped.

They stopped moving and stared at each other in amazement. If there had been any doubts before, they were gone now. There was no denying the evidence; former Alpha turned Omega Sherlock Holmes had his cock snugly held inside new Alpha Molly Hooper’s cunt by her vagina dentata.

“Oh,” Molly breathed, carefully resting her body against his. “ _This_ is new…”

*                       *                                               *                                            *                             *

They remained like that for nearly an hour before the vaginal teeth retracted back in and they could disengage their bodies. They showered quickly and drank more water, the Heat a ticking clock over their heads. They could have a few hours, or even a day at this point. But there would likely be several more episodes of the Heat taking them before it was over. They sat on the sofa, sipping from their glasses, not bothering putting on clothes because it was ridiculous to dress only to undress again.

It wasn’t until Sherlock had absently scratched at his neck the second time that it caught Molly’s attention. When he moved his hand away, she looked at the area and gasped sharply.

He frowned. “What?”  

“Sherlock. Your neck,” Molly said in alarm.

He rose and headed for the loo, Molly behind him. He switched on the light and stepped to the mirror, turning his head, his eyes narrowed in concentration.  But there was no need to focus to see this; it was obvious to someone who knew what to look for. The place on his neck, where Molly had first bitten him in ritual manner, had altered. The redness was gone. In its place, pale but unmistakable, was a silvery, scar-like imprint of her teeth.

Sherlock drew a swift, startled breath. There was no mistaking it. It was The Mark of Bonding. They were fully compatible on the most basic, yet most complex level possible. If they were not, he would still bear the ordinary characteristics of a love bite. Normally, the Mark didn’t show until the second day, and the bonding continued to solidify over the cycle, to reach completion at the end. Apparently the stages of his Heat were not all that had accelerated.

“Oh,” he said, knowing it sounded ridiculous but unable at the moment to form any other words.

Molly glanced down. “I-we-it doesn’t have to mean anything.”

“You know as well as I do it’s a little late for that,” Sherlock said. He turned and cupped her chin, making her meet his gaze. “I offered myself to you, Molly,” he said softly. “I bared my throat to you in ritual assent. Surely you must know I did that in full awareness of what the results could be.”

“But why?” She asked, confused. “I mean, I know I accepted, but I was overcome by my instincts. You still had some rationale left. Why did you offer, knowing that could happen?”

He sighed. “Because I wanted to. A romantic partnership with you, while carrying with it the factors of distraction and sentiment, eliminates other problematic elements such as loneliness. Since John and Mary wed, I have missed companionship, and found myself wanting more of yours. We are intellectually compatible; well, inasmuch as possible considering my mind is extraordinary and yours is only above average. We share common interests and our work coincides frequently. We have mutual trust and respect.”

“Sherlock, are you telling me you logically decided to offer me your throat to test and see if we could bond…because you thought it would be a good idea?”

He blinked. “Yes. Was that wrong?”

Molly sighed. “It’s very you. But I guess I was hoping for more. That maybe you, I dunno, had some feelings for me.”

Sherlock sighed. “Molly…do you really think I would have done this out of intellect alone? Especially knowing how you feel about me?”

She stared. “Then…”

“Yes, Molly. I care for you. Would I have acted on it, were it not for this mishap? I don’t know. But I don’t regret it. I realize there are many details we’ll need to discuss. But given that I feel my heat returning yet again, perhaps we should leave that discussion until this is all over?”

As if on cue, Molly inhaled sharply. Sherlock felt his pulse elevate in response as the heat uncurled in his groin and started to spread through him again like wildfire. God this was distracting. No. Obliterating. He’d definitely need suppressants. Although they should probably share a heat twice a year, to regulate the hormones fully and nurture the bond…

The rational thoughts Sherlock was trying to cling to shattered like the broken beakers in the lab when his lips found Molly’s again.

*               *                           *                                    *                                     *                                               *                                              *

Mycroft Holmes was at his desk, fingers laced together and tucked under his chin, when his mobile rang.

“Yes?” he asked politely when he answered.

He listened to the other voice on the line, a slight frown marring his features. “And you are certain that the transformation was successful?”

His face smoothed out as he processed the information he was given, eyebrows raising a fraction on his forehead. “And they are still in Sherlock’s flat at Baker Street?”

He nodded at the affirmative. “Excellent. Keep me informed. No, I don’t want it recorded. It is a private matter between him and Doctor Hooper. Simply notify me of when they leave and what their destination is. Most likely, it will be St. Bartholomew’s Hospital. I will go see them personally once everything is more settled.”

He ended the call and returned his mobile to his desk, a look of satisfaction on his face. There would be questions, he knew; accusations of meddling, violating privacy, and whatever else his brother could come up with. At the end of the day, however, both he and Doctor Hooper would be forced to admit that they now had exactly what they wanted.

 No longer would Sherlock be at the mercy of the Alpha hormones he despised, and no longer would Doctor Hooper feel small and unassuming. Their bonding (and Mycroft knew they were compatible, had known they would be for ages, even if Sherlock had wanted to deny the truth) would be a benefit to them both. And to Mycroft; no longer needing to worry about his brother’s moods, his unchecked Alpha urges, his secret quest for a “cure” that was really not so secret.

No, it was better for everyone, this new development.

Which was, of course, why Mycroft had engineered it to begin with.

**Works inspired by this one:**

  * [Converto](https://archiveofourown.org/works/3297173) by [o0katiekins0o](https://archiveofourown.org/users/o0katiekins0o/pseuds/o0katiekins0o)




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